If "no pain, no gain" is your motto, it's time to re-think your workout plan

Dreyer sees heel strike in both veteran runners and beginners training for their first 5K. "With heel strike, every time you're taking a stride, you're putting on the brakes," says Dreyer. "It makes your running less efficient and contributes to injuries."

Second runner-up mistake: you're stretching like a rubber band before you start running. "If you watch Olympic athletes, they're not doing hamstring stretches before a race. They're jumping around, keeping their body warm and shaking it out," Dreyer says.

The Fix: Instead of running by sticking your legs out in front of you, focus on your legs landing underneath you. Lean your body forward (without falling on your face) instead of leaning back. Dreyer says the best shoes to prevent heel strike are those with minimal construction. Vibrams, anyone?

And about all of that stretching? A light warm up run and shaking and loosening the body will do more good than stretching cold muscles. Likewise, runners who don't do a cool down jog after a race are running the risk of muscle contraction and cramps.

Avoid Injury:"Preparing for a race is like coming up with a really good business plan," says Dreyer. If you've prepared, you should have worked out all the kinks that might pop up. But, if you find yourself hobbling mid-race, or experiencing sharp, shooting pain, Dreyer says you need to slow down, shorten your stride and assess what is hurting.